error_reporting(E_ALL);

This function will tell PHP to display any errors it might encounter while executing this script. Please copy the error message and post it here

$blacklist = array(“.php”, “.phtml”, “.php3?, “.php4?, “.php5?, “.exe”, “.js”,“.html”, “.htm”, “.inc”);

You’re missing some closing double-quotes in your blacklist array. It should be like this:

$blacklist = array(“.php”, “.phtml”, “.php3?”, “.php4?”, “.php5?”, “.exe”, “.js”,“.html”, “.htm”, “.inc”);

It should work now. You were getting a blank page because of a PHP error. You should enable PHP to display errors in your scripts in order to let you know when something goes wrong (but use it only on testing enviroments, never on production enviroments!).

Let me know if it worked, ok?

<?php
// Upload directory: remember to give it write permission!
$uploaddir = “upload/”;
// what file types do you want to disallow?
$blacklist = array(“.php”, “.phtml”, “.php3?, “.php4?, “.php5?, “.exe”, “.js”,“.html”, “.htm”, “.inc”);
 // allowed filetypes       
$allowed_filetypes = array(‘.jpg’,‘.gif’,‘.bmp’,‘.png’);
 
if (!is_dir($uploaddir)) {
    die (“Upload directory does not exists.”);
}
if (!is_writable($uploaddir)) {
    die (“Upload directory is not writable.”);
}
 
if ($_POST['submit']) {
 
    if (isset($_FILES['file'])) {
        if ($_FILES['file']['error'] != 0) {
            switch ($_FILES['file']['error']) {
                case 1:
                    print ‘The file is too big.’; // php installation max file size error
                    exit;
                    break;
                case 2:
                    print ‘The file is too big.’; // form max file size error - DEPRECATED
                    exit;
                    break;
                case 3:
                    print ‘Only part of the file was uploaded’.;
                    exit;
                    break;
                case 4:
                    print ‘No file was uploaded.’;
                    exit;
                    break;
                case 6:
                    print “Missing a temporary folder.”;
                    exit;
                    break;
                case 7:
                    print “Failed to write file to disk”;
                    exit;
                    break;
                case 8:
                    print “File upload stopped by extension”;
                    exit;
                    break;
            }
        } else {
            foreach ($blacklist as $item) {
                if (preg_match(“/$item\$/i”, $_FILES['file']['name'])) {
                    echo “Invalid filetype !”;
                    unset($_FILES['file']['tmp_name']);
                    exit;
                }
            }
            // Get the extension from the filename.
            $ext = substr($_FILES['file']['name'], strpos($_FILES['file']['name'],‘.’), strlen($_FILES['file']['name'])-1);
// Check if the filetype is allowed, if not DIE and inform the user.
if(!in_array($ext,$allowed_filetypes)){
die(‘The file you attempted to upload is not allowed.’);
}
if (!file_exists($uploaddir . $_FILES["file"]["name"])) {
// Proceed with file upload
if (is_uploaded_file($_FILES['file']['tmp_name'])) {
//File was uploaded to the temp dir, continue upload process
if (move_uploaded_file($_FILES['file']['tmp_name'], $uploaddir . $_FILES['file']['name'])) {
// uploaded file was moved and renamed succesfuly. Display a message.
echo “Upload successful!”;
} else {
echo “Error while uploading the file, Please contact the webmaster.”;
unset($_FILES['file']['tmp_name']);
}
} else {
//File was NOT uploaded to the temp dir
switch ($_FILES['file']['error']) {
case 1:
print ‘The file is too big.’; // php installation max file size error
break;
case 2:
print ‘The file is too big.’; // form max file size error
break;
case 3:
print ‘Only part of the file was uploaded’;
break;
case 4:
print ‘No file was uploaded’;
break;
case 6:
print “Missing a temporary folder.”;
break;
case 7:
print “Failed to write file to disk”;
break;
case 8:
print “File upload stopped by extension”;
break;
}
}
} else { // There’s a file with the same name
echo “Filename already exists, Please rename the file and retry.”;
unset($_FILES['file']['tmp_name']);
}
        }
    } else { // user did not select a file to upload
        echo “Please select a file to upload.”;
    }
} else { // upload button was not pressed
    header(“Location: form.html”);
}
?>

If it doesn’t work please let me know. I may give you a hand with your script if you allow me to do so.

Give it a try and let me know if it worked, ok?